Chimaera

A chimera is an organism composed of cells with different genetic origins, typically resulting from the fusion of two different zygotes early in development. This means it has tissues or cells that contain genetic material from two distinct individuals. In humans, chimeras can occur naturally, such as when twin embryos merge during pregnancy, or artificially through medical procedures like bone marrow transplants. The result is an individual with a mosaic of genetic makeup, which can sometimes lead to unique physical traits or medical conditions, often remaining unnoticed without detailed genetic testing.